Kvaerner Pulping Ab

Glv Finance Hungary Kft., Luxembourg Branch

Martin Ragnar

Hakan Dahllof

Hakan Dahllöf

The invention relates to a method and arrangement for alkaline oxygen delignification of cellulose pulp. By adding alkali in the final phase of the oxygen delignification one can ensure that an optimal predetermined end-pH is obtained. This provides advantages in the subsequent bleaching since the bleachability is substantially improved in the form of reduced need for bleaching chemicals.

Method and arrangement for oxygen delignification of cellulose pulp

Method for enabling the paper pulp production process to be controlled in such a way that the hexenuronic acid content in the pulp can be minimized and the color reversion of the pulp and/or the pulp products thereby minimized. The method is based on measurements of the optical properties of a fiber containing substance or process stream in the wavelength region 232&#xb1;5 nm and another wavelength interval. A significant value for the current hexenuronic acid content is formed by correcting the intensity in the spectrum around 232 nm by the corresponding optical quantity at the other wavelength interval. The content of the hexenuronic acid content that is determined by the analysis is then used for controlling conditions in the process stage.

Method for regulating the manufacturing of pulp by optically measuring the amount of hexenuronic acid

A system and process for the oxygen delignification of pulp consisting of a lignocellulose-containing material that has a mean concentration of 8-18% pulp consistency. The oxygen delignification takes place in a first stage with a short dwell time of about 3-6 minutes, at a low temperature of about 85&#xb0; C. and under a low pressure of approximately 0-4 bar. A concluding stage has a longer dwell time of about 50-90 minutes, at a higher temperature of approximately 100&#xb0; C. and under a higher pressure of about 8-10 bar.

Process for the oxygen delignification of pulp in two stages with higher pressure in the second stage

The system is for the oxygen delignification, in at least two reaction stages, of pulp that consists of lignocellulose-containing material having a mean concentration of 8%-18% pulp consistency. The oxygen delignification takes place in a first reaction stage that has a substantially constant low pressure during the whole delignification process. The second delignification stage has a substantially higher pressure and temperature and a longer dwell time. Readily delignifiable constituents in the pulp may react without the pulp being negatively affected so that the delignification process provides a very high degree of selectivity and an improved yield.

System for the oxygen delignification of pulp consisting of lignocellulose-containing material

A system and a process for the oxygen delignification of pulp consisting of lignocellulose-containing material whose mean concentration is 8-18% pulp consistency, in at least two stages. The invention is characterized in that the oxygen delignification takes place in a first stage with a short dwell time of approx. 3-6 minutes, at a low temperature of approx. 85&deg; C. and under a low pressure of approx. 0-4 bar, followed by a concluding stage with a longer dwell time of approx. 50-90 minutes, at a higher temperature of approx. 100&deg; C. and under a higher pressure of approx. 8-10 bar. This makes it possible, in an industrial process, to exploit the kinetics of the oxygen delignification in an optimal manner for the purpose of obtaining a selective oxygen delignification at low installation cost and at low operating cost.

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Karlstad, Sweden

Martin Ragnar